Effect of in vitro gastrointestinal digestion on the bioaccessibility of polyphenolic compounds of flours obtained from lemon and cactus pear fruit co-products.

The flours obtained from several co-products like lemon (Citrus lemon) or cactus pear fruit (Opuntia indica) contains a wide range of bioactive compounds mainly dietary fiber and polyphenolic compounds. In this work, the bioaccessibility of polyphenolic compounds (phenolic acids and flavonoids) present in the flours obtained from lemon (LF) and cactus pear (CPF) was tested by the application of in vitro gastrointestinal digestion. In vitro gastrointestinal digestion of samples was performed according to the method described by Mills et al. (2008) while the bioaccessibility of polyphenolic compounds was determined following the indications of Ortega et al. (2011). The bioaccessibility index of phenolic acids present in LF and CPF, at the end of intestinal digestion, were 18.25 and 46.53%, respectively with statistical differences (p<0.05) between them. The bioaccessibility of flavonoid compounds in LF and CPF, at the end of intestinal digestion, was 13.94 and 11.32% respectively, with statistical differences (p<0.05) between them. These values suggest that several changes in phenolic and flavonoid compounds like modification of chemical structure, increased or reduced solubility or interaction with other compounds might happen during the gastrointestinal digestion of co-product flours, which influence the bioaccessibility as mentioned Gullon et al. (2015).